dysrow1
There are in total 21 factions and there can be no more then 21 factions. You can replace one of them, but keep in mind the following things:
- 1 Senate faction: that needs to be placed in Rome, hence both the Senate and Rome are needed to make the game run. The Senate faction is unplayable in the sense that it will cause CTDs when pressing some buttons.
- 3 Roman factions: these are hard-coded as part of the Roman government thingie.
- 17 other factions.

Some people have discovered that some Roman factions have been coded to always start with attacking certain regions/factions. It would be worthwhile to analyze the normal campaigns to use the coding for your own goals.